This invention relates generally to illuminating panels. More particularly, this invention relates to cost effective systems and methods for using multiple point light sources such as light emitting diodes (LEDs) to illuminate panels.
Illuminated panels have many uses where evenly lit panels with neutral color temperature are used including advertising display panels, shopping mall directories, restaurant menus, event schedules, and navigational signboards. Other uses for illuminated panels include light-boxes for artists, photographers, architects, design engineers, general contractors and draftsmen.
These illuminated panels can be as small as six inches by six inches, and as large as four feet by eight to ten feet or more. Depending on their specific applications, weight, cost, panel thickness, and lamp-life, can all be crucial to the successful design, manufacture and marketing of these panels. In addition, environmental requirements such as vibration/shock resistance, impact resistance, operating temperature range, ease of maintenance and power consumption can also be important.
Fluorescent light tubes are used in most commercially available illuminated displays because of the inherent evenness of light output due to the tube's physical configuration. In addition, fluorescent lamp-life is significantly longer than incandescent bulbs, and fluorescent lights also consume significantly less power for the same light output. While fluorescent tubes are better than incandescent bulbs for illuminating panels, they also have many disadvantages including overall size and weight of the power supply, and fragility of the glass tube. For example, because most illuminated panels are less than one-half of an inch thick, the fluorescent tubes have to be equally skinny and very fragile. Accordingly, the fluorescent tubes are easily damaged during manufacture, transportation and installation.
In addition, although fluorescent tubes have longer lamp-life than incandescent bulbs, fluorescent tubes have a tendency to flicker depending on the frequency of the driving voltage. The light output of fluorescent tubes is also not easily adjusted to match ambient light conditions. Ballasts are also required for operation of the fluorescent tubes. Fluorescent tubes are also inefficient when operated under low temperatures.
There are also other disadvantages inherent with using single light sources, the most common of which are fluorescent tubes. Since fluorescent tubes are easily damaged when subjected to shock, when the single fluorescent tube fails, an entire side of the panel is not longer illuminated.
Previous attempts at replacing fluorescent tubes with point lights sources have failed because point light sources produce a “saw-tooth” effect in the light pattern. It is therefore apparent that an urgent need exists for improved illuminated panels using point light sources that are easy to manufacturer, easy to maintain, shock resistant, impact resistant, portable, cost effective, and have long lamp-life.